A typical data storage disk drive comprises at least one disk on which data is stored in magnetic or optical form, a head mounted on an arm to read/write from the disk surface and necessary control circuits. The disk is rotated at a constant velocity by a spindle motor and the arm is moved over the disk surface to access different locations on the disk surface by a voice coil motor (VCM). Upon power failure, in order to avoid physical damage to the disk storage surface as well as the read/write heads, the read/write head assembly should be positioned away from the disk data storage surface (referred to as parking the arm). Under power failure conditions the energy required to drive the voice coil motor may have to be derived from a secondary source, and in this case energy remaining in the spindle motor can be used by the disk drive circuits to operate the voice coil motor to park the arm.